Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C7/00—Orthodontics, i.e. obtaining or maintaining the desired position of teeth, e.g. by straightening, evening, regulating, separating, or by correcting malocclusions
  • A61C7/12—Brackets; Arch wires; Combinations thereof; Accessories therefor
  • A61C7/20—Arch wires
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C7/00—Orthodontics, i.e. obtaining or maintaining the desired position of teeth, e.g. by straightening, evening, regulating, separating, or by correcting malocclusions
  • A61C7/12—Brackets; Arch wires; Combinations thereof; Accessories therefor
  • A61C7/14—Brackets; Fixing brackets to teeth
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C8/00—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools
  • A61C8/0012—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools characterised by the material or composition, e.g. ceramics, surface layer, metal alloy
  • A61C8/0013—Means to be fixed to the jaw-bone for consolidating natural teeth or for fixing dental prostheses thereon; Dental implants; Implanting tools characterised by the material or composition, e.g. ceramics, surface layer, metal alloy with a surface layer, coating
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/28—Materials for coating prostheses
  • A61L27/30—Inorganic materials
  • A61L27/303—Carbon
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L29/00—Materials for catheters, medical tubing, cannulae, or endoscopes or for coating catheters
  • A61L29/08—Materials for coatings
  • A61L29/10—Inorganic materials
  • A61L29/103—Carbon
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/08—Materials for coatings
  • A61L31/082—Inorganic materials
  • A61L31/084—Carbon; Graphite
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1633—Process of electroless plating
  • C23C18/1655—Process features
  • C23C18/1662—Use of incorporated material in the solution or dispersion, e.g. particles, whiskers, wires
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/31—Coating with metals
  • C23C18/32—Coating with nickel, cobalt or mixtures thereof with phosphorus or boron
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D15/00—Electrolytic or electrophoretic production of coatings containing embedded materials, e.g. particles, whiskers, wires
  • C25D15/02—Combined electrolytic and electrophoretic processes with charged materials
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/56—Electroplating: Baths therefor from solutions of alloys
  • C25D3/562—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of iron or nickel or cobalt
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/34—Pretreatment of metallic surfaces to be electroplated
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1633—Process of electroless plating
  • C23C18/1646—Characteristics of the product obtained
  • C23C18/165—Multilayered product
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/13—Hollow or container type article [e.g., tube, vase, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
  • Y10T428/264—Up to 3 mils
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31511—Of epoxy ether
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31551—Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]
  • Y10T428/31609—Particulate metal or metal compound-containing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31678—Of metal
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers

Definitions

• This invention relates to the field of dental and medical articles, such as orthodontic archwires, brackets, catheters, implants and needles. More specifically, the invention relates to dental articles and articles for use in medicine in general, having a friction-reducing coating.
• Orthodontics is a dental specialty, which aims to bring about changes in the location of abnormally positioned teeth. This is achieved by application of continuous mechanical load
• the orthodontic treatment has become very common in recent decades and also adults have begun seeking this treatment for esthetic and functional reasons.
• the most common orthodontic technique consists of a rigid wire (also termed
• archwire which is inserted into slots incorporated within special attachments (orthodontic brackets) being bonded on the teeth, as illustrated in Fig. 1.
• the basic principle of orthodontic appliances in the archwire technique is to apply mechanical forces on teeth so that movement will occur in every desirable spatial direction. The forces are applied during the various stages of treatment by a variety of appliances, which include several kinds of archwire, ligatures, brackets and bands.
• Friction among appliances used for orthodontic correction of teeth is recognized by clinicians as a hindrance to tooth movement. Friction reduces the effective force, which is applied to the tooth from the wire, hi the case of sliding mechanics, excessive friction, brought about by the angle between the wire and the slot of the bracket, slows tooth movement down substantially or even halts it.
• a factional type force that resists the movement of the tooth and accompanies the sliding of a tooth along an archwire is referred to as resistance to sliding (RS).
• the archwire size, shape, material and surface.
• the bracket material, size and shape of the slot and its edges, surface of slot and the angle formed between the wire and the slot.
• U.S. Patent No. 5,288,230 describes applying a coating of diamond-like carbon (DLC) onto archwires to serve as a barrier to diffusion of nickel and chromium from the wire and also provide a hard, friction-reducing surface.
• U.S. Patent No. 5,454,716 describes a coating of a plastic-ceramic composite, which is aesthetically pleasing, but is susceptible to localized abrasion over time.
• Another method is described in U.S. Patent No. 6,299,438 and comprises applying a friction-reducing coating containing iridium or platinum to a metal and/or ceramic dental article which is first coated with an adhesion metal layer.
• Screw-type dental implants are made in two general types.
• the first type is a self-tapping implant that can be threaded into a pre-drilled bore in a jawbone without pre-tapping the bore.
• the second type is a non-self-tapping implant that requires pre-tapping of the bore.
• the implant has a generally cylindrical main body which bears one or more external screw threads on its outer surface. These external thread(s) engage corresponding internal thread(s) cut into the wall of the bore to provide initial stabilization of the implant in the bore.
• the friction encountered by dental implants is proportional to the penetration depth of the implant into the bone, the diameter of the bore, and the hardness of the bone at the site of the bore.
• the torque that must be applied to insert the implant into the bore is proportional to the friction.
• High torque puts strains on the implant, on the tools used to place the implant in the bore, and on the bone.
• there is a greater risk of damage to the implant, the tools, and the bone Consequently, there is a continuing need to design a screw-type dental implant which minimizes the torque needed to install it into living jawbone.
• the present invention provides an article for use in medicine or dentistry, being coated at least partially by inorganic fullerene-like (IF) nanoparticles or a composite containing such nanoparticles.
• IF inorganic fullerene-like
• the present invention further provides methods for coating articles for use in medicine or dentistry with inorganic fullerene-like (IF) nanoparticles or a composite containing such nanoparticles.
• IF fullerene-like
• the present invention thus provides an article, preferably elongated, at least part of it being coated by inorganic fullerene-like (IF) nanoparticles or composite containing IF nanoparticles.
• IF inorganic fullerene-like particles
• the inorganic fullerene-like (IF) particles are self-lubricating and thus reduce friction between the article and adjacent object, surface or tissue, as compared to uncoated article.
• the article of the present invention is preferably made of metal, plastic, rubber or glass. More preferably, the article is made of metal.
• an "elongated article” within the context of the present invention is an article extending preliminarily along one axis (i.e. length) while having smaller dimensions along the other perpendicular two axes (i.e. thickness and cross-section).
• the elongated article has a cross-section in the range of about a centimeter or less, preferably of about several millimeters or less. Nevertheless, elongated articles with cross-sections larger than about a centimeter are also within the scope of the invention, as long as they are used in medicine or dentistry.
• Non limiting examples of elongated articles are needles, catheters and archwires.
• the coated article is used in dentistry e.g. in orthodontic appliances or dental implants.
• the article is either circular or rectangular in cross-section and has the form of a wire or elongated hollow tube.
• at least part of the article of the invention is coated by friction reducing film comprising inorganic fullerene-like (IF) nanoparticles or composite containing IF nanoparticles.
• -wire as used herein includes, for example, an archwire used in orthodontics.
• inorganic fuller ene-like (IF) particles or “inorganic fullerene-like (IF) nanoparticles” within the context of the present invention covers hollow and non- hollow nanoparticles of transition metal chalcogenides and dichalcogenides, made up of single or multi-layers and having structures such as spheres, tubes, nested polyhedra, onion-like and the like.
• a “transition metal” inlcudes all the metals in the periodic table from titanium to copper, from zirconium to silver and from hafnium to gold.
• the transition metals are selected from Mo, W, V, Zr, Hf, Pt, Pd, Re, Nb, Ta, Ti, Cr and Ru.
• a "chalcogen” as used herein refers to S, Se or Te.
• the metal chalcogenides and dichalcogenides are preferably selected from TiS 2 ,
• the metal chalcogenides and dichalcogenides are selected from WS 2 and
• Inorganic fullerene-like WS 2 (IF-WS 2 ) was first reported by Tenne and co- workers in 1992 [Tenne R. et al, Nature 360: 444-445 (1992) and U.S. Patent No. 5,958,358]. It was shown that under a certain reducing and sulfidizing atmosphere at elevated temperatures, tungsten oxide nanoparticles could fold and form nested WS 2 fullerene-like nano-structures with layers that resemble an onion. The size of these nanoparticles range from tens to several hundreds of nanometers, depending on the WO 3 precursor's size. Surprisingly, the inventors have found that IF particles are biocompatible.
• biocompatible ZP particles may be used in biological systems in humans to alleviate friction problems. Consequently, the present invention provides in one of its aspects, biocompatible article, preferably made of metal, at least part of it being coated by friction reducing film comprising inorganic fullerene-like (IF) particles or composite containing IF particles.
• IF fullerene-like
• Biocompatible article is defined for purposes of this description as article that can be used in animals, particularly humans without a significant adverse biological
• host response e.g., foreign body reaction, autoimmune disease, necrosis, apoptosis
• a preferred embodiment of the present invention also provides an improved screw-type dental implant that reduces the torque required to install the implant by reducing the friction between the implant and the sidewalls of the bore, at least a portion of the implant being coated by friction reducing film comprising inorganic fullerene-like (IF) particles or composite containing IF particles.
• IF fullerene-like
• composite refers to solid material made from two or more components.
• One component is often fibers or particles, such as graphite fibers, BN-whiskers and ZF-nanoparticles, that give the material its tensile strength, while another component (called a matrix), such as Ni-P, polyurethane and epoxy, binds the fibers or particles together.
• a matrix such as Ni-P, polyurethane and epoxy
• Non-limiting examples of composite according to the present invention are Ni-P-ZF-nanoparticles , any metal film, like Pt containing IF- nanoparticles, polymer (e.g. polyurethane or polypropylene) or epoxy containing IF- nanoparticles or a sol-gel glass containing ZF-nanoparticles.
• the term "friction-reducing film” refers to a film or layer of an article capable to reduce the surface friction coefficient of that article, as measured with a ball-on-flat device by at least 20% when compared to the friction coefficient of the uiicoated article.
• the article of the invention being coated at least partially with a friction reducing film is used in dentistry and medicine and is selected from all types and sizes of orthodontic archwires, all types of orthodontic brackets, dental implants, bands, all types of bonded or banded orthodontic attachments and, palatal expanders used to orthodontically expand lower and upper dental dentitions.
• the friction reducing film can be also used to reduce friction in mobile functioning native or artificial human joints including temporo-mandibular joint, knee, ankle, elbow etc and also in hip replacement.
• Coating needles or catheters, which penetrate human tissues, with the friction reducing film of the invention will significantly reduce tissue damage adjacent to these medical devices during the insertion procedure.
• Further uses of low friction medical instruments are feeding oral and nasal tubes as well as the various tubes used for laparoscopic surgeries.
• the articles may be made of any metals suitable for use in dental and medical devices, for example stainless steel, iridium, platinum, palladium, rhodium, rhenium, alumina, zirconia, nickel-titanium, gold, silver, titanium, titanium- molybdenum alloy (TMA), beta-titanium and blends or alloys of these.
• the friction reducing film comprises biocompatible IF nanoparticles or composite containing such nanoparticles, capable of reducing the surface friction of the coated article (compared to the uncoated article) so that metal pieces e.g. pieces of the dental article which are connected together and cooperate with each other, e.g., archwires and brackets, can slide past each other more easily, thereby allowing for easier and more precise adjustment by the orthodontist or dentist.
• the coating preferably also has the properties of being resistant to mechanical wear and sufficiently inert to resist degradation in the environment of the mouth.
• the inventors developed a method for reducing friction between an article used in medicine or dentistry and adjacent surface, tissue or object, by coating at least part of the article's surface by inorganic fullerene-like (IF) nanoparticles or composite containing such nanoparticles.
• IF inorganic fullerene-like
• the present invention provides a method for reducing friction between a dental article and other articles or the tooth, said article being selected from dental implant, orthodontic wire, orthodontic bracket, band, bonded or banded orthodontic attachment, palatal expanders, the method comprising coating at least part of the article's surface with a friction-reducing film, said film comprising inorganic fullerene-like (IF) nanoparticles or composite containing such nanoparticles.
• IF inorganic fullerene-like
• the method is preferably adapted for coating wires and similar tubular structures that are characterized by different morphologies in comparison to flat substrates.
• the present invention provides a method for coating an article for use in medicine or dentistry with a friction reducing film, the method comprising:
• the method comprises prior to contacting the article with the plating solution exposing the article to a surface pre-treatment procedure.
• the pre-treatment procedure is carried out with an etching acidic solution, for example HF etching solution.
• the method comprises one or more additional deposition steps prior to said contacting to form intermediate layers between the article and the outer, friction reducing film.
• the method further comprises annealing the coated article at high temperature.
• the article is a metallic wire.
• the wire is a wire used in orthodontic appliances and is usually made of stainless steel, iridium, platinum, palladium, rhodium, rhenium, gold, silver and blends or alloys of these.
• the article is also exposed to e- beam deposition of Ni-Cr and/or Ni before the deposition of the friction reducing film.
• the friction reducing film may be applied by any technique which is useful for depositing metallic coatings onto metallic substrates, for example, electroless deposition and electrodeposition, sputtering, chemical vapor deposition, ion beam enhanced deposition, plasma-assisted vapor deposition, cathodic arc deposition, ion implantation and evaporation, most preferably being electroless deposition and electrodeposition.
• the plating solution comprises Ni or Co, phosphate or borate salt, reducing agent e.g. citrate, and surfactant and the article obtained by the method of the invention is coated with a friction-reducing film comprising composite of Ni-P, Co-P, Ni-B or Co-B and IF nanoparticles.
• the article is coated with a polymer (e.g. polyurethane or polypropylene) or epoxy coating.
• a polymer e.g. polyurethane or polypropylene
• epoxy coating e.g. epoxy
• a sol-gel glass coating is applied on the article.
• the article is coated with IF- nanoparticles.
• nanoparticles powder such as IF- WS 2 powder, may be burnished with cloth for 15 minutes and then the article may be also burnished with the cloth until a thin coating of the ZF-WS 2 is applied on the article, which serves as a self-lubricating coating.
• Fig. 1 is a photograph illustrating the orthodontic setup of a fixed orthodontic appliance.
• Fig. 2 is a SEM magnification x 12000 of Ni-P coating on SS wire.
• Figs. 3A and 3B show TEM images of single ZF-WS 2 nanoparticles after ultrasonic dispersion within a Ni-P matrix after 2 minutes of sonification and one hour of plating activity, respectively.
• Figs. 3C and 3D show an enlarged TEM image of the IF where the layers are observed with no apparent damage.
• Fig. 4 is an optical micrograph of the surface of a Ni-P-ZF-WS 2 film, after 100 cycles of dry friction.
• Fig. 5 shows optical micrographs of the surface of Si 3 N 4 ball after the friction with Ni-P-ZF coating using Mouth Kote fluid (A) - Before cleaning, (B) - After cleaning.
• Fig. 6 is a graph showing the friction coefficient of the orthodontic wire vs. number of cycles, compared to a wire coated with Ni-P-WS 2 composite.
• Fig. 7A is a graph of force (N) vs. displacement (mm) in non coated SS wire, taken at 0° angle of contact between the bracket and the wire; average force is 1.32N (STANDARD DEVIATION (SD)) -0.12).
• Fig. 7B is a graph of force (N) vs. displacement (mm) in coated wire, taken at
• Fig. 10 is a photograph of the bracket-mounting apparatus.
• Fig. 11 is a photograph of an angulation device with an aluminum plate screwed in the 10° angle slot.
• Fig. 12 is a photograph showing an orthodontic wire inserted into the bracket slot and ligated by an elastic module. The wire is connected on the top to the load cell and on the bottom to the 150g weight.
• the present invention provides an article for use in medicine or dentistry, preferably made of metal, at least part of its surface being coated by friction reducing film comprising inorganic fullerene-like (IF) nanoparticles or composite containing such IF nanoparticles.
• IF fullerene-like
• the article may be, for example, an elongated article such as a metallic wire e.g. orthodontic archwire or elongated medical article e.g. needle, catheter, etc.
• the present invention further provides methods for coating the articles with a friction-reducing film which comprises IF nanoparticles or composite containing such nanoparticles.
• the article When the article is a dental article, it may comprise a metallic article which is placed temporarily or permanently in the mouth of an individual.
• Such articles include, for example, orthodontic appliances such as archwires or screw-type dental implants.
• the orthodontic wires or dental implants may be comprised of any metals suitable for use in dental devices, for example stainless steel, titanium, titanium-molybdenum alloy (TMA), beta-titanium, nitinol, alumina, zirconia, nickel-titanium, and alloys and blends of these materials. Beta-titanium, stainless steel and nickel-titanium alloys are currently preferred archwire materials.
• the coated wire of the invention also may include one or more additional intermediate layers between the wire and the outer, friction-reducing film.
• the intermediate layer(s) preferably comprise a metallic material selected from the group consisting of Ni and Ni-Cr.
• One method of applying the friction reducing film is by incorporating the IF nanoparticles into a coating by composite electroless deposition. Electroless plating has gained popularity since the beginning of the last century when it was first introduced, due to the production of coatings with excellent corrosion, wear and abrasion resistance.
• Electroless plating is a chemical process of oxidation and reduction by which a metallic ion is reduced from an aqueous solution containing a reducing agent onto a surface having a catalytic site with no need to transfer a current.
• nickel and cobalt have proven supremacy in corrosion and wear resistance when deposited as nickel phosphorus (Ni-P), cobalt phosphorus (Co-P), or mixtures of Co-P or Ni-P with other transition metals such as for example Co-Ni-P, Co-Rh-P, Co-W-P or Co-Fe-P.
• Ni-P nickel phosphorus
• Co-P cobalt phosphorus
• Ni-P cobalt phosphorus
• Ni-P nickel phosphorus
• Co-P cobalt phosphorus
• Ni-P nickel phosphorus
• Co-P cobalt phosphorus
• Ni-P nickel phosphorus
• Co-P cobalt phosphorus
• Ni-P nickel phosphorus
• Co-P cobal
• Another way of coating an article with a friction reducing film is by electrochemical deposition, hi this way the article is first exposed to a surface pre- treatment procedure. In the next step, the article is immersed in a metal solution and a current is applied. A similar solution containing IF nanoparticles is then prepared by sonication and the article is immersed in this solution and a current is applied. Alternatively, the article is first immersed in a metal solution, such as Cr or Ti and then in the next step is immersed in another solution of Ni-P or Cr containing the IF nanoparticles.
• a metal solution such as Cr or Ti
• the metal solution for the electrochemical deposition may be any metal solution.
• the metal may be Ni, Pt, Co, Cr, Fe, or alloys thereof.
• the article is coated with a polymer (e.g. polyurethane or polypropylene) or epoxy coating.
• the polymer is heated until a non-viscous polymer is obtained and then ZP-nanoparticles are added.
• the article is painted with the polymer or immersed in the polymeric solution. Then the polymer is treated by curing (radiation) or by cross-linking (e.g. with UV light).
• a sol-gel glass coating is applied on the article.
• Another way of coating an article with a friction reducing film is implemented by burnishing nanoparticles powder with cloth for a few minutes and then burnishing the article with the cloth until a coating of the nanoparticles is applied on the article, which serves as a self-lubricating coating.
• Electroless Ni-P coatings on stainless steel (SS) orthodontic wires Fig. 2 shows a smooth, homogenous film of electroless Ni-P on a stainless steel wire.
• the scotch bond test caused peeling of the coating, as opposed to a same test carried on a stainless steel plate coated with similar Ni-P film by electroless deposition, indicating poor adhesion to the wire substrate.
• the SEM images of the two substrates showed different microscopic morphology in spite of having the same SS composition. This difference in the surface morphology is suggested to be the cause to the poor adhesion of Ni-P film exhibited by the wires as opposed to plates.
• TMs was achieved by agitating a dispersion of the WS 2 nanoparticles in the electroless bath (commercially available solution sold under the name Enplate Ni-425, Enthone Inc.) by ultrasonic stirrer and also by the use of suitable surfactants.
• surfactants i.e. anionic (SDS-sodium dodecyl sulfate), cationic (CTAB-cetyl trimethyl ammonium bromide) and non-ionic (Triton-x), CTAB seemed to show the best results.
• Figs.3A and 3B show TEM images of single IP-WS 2 nanoparticles after ultrasonic dispersion within a Ni-P matrix after 2 minutes of sonification and one hour of plating activity, respectively.
• Figs. 3C and 3D show an enlarged TEM image of the IF where the layers are observed with no apparent damage.
• the electroless reaction was carried out first by treating the wire with an HF solution, in- order to cause pitting of the substrate and consequently mechanically enhance the adhesiveness of the coating to the wire substrate.
• the wire was subjected to electroless coating in a commercially available plating bath containing essentially IF particles, Ni and phosphate, to obtain a wire coated with composite Ni-P- ZF-WS 2 film that had adequate adhesive strength to the wire surface (adequate adhesive strength as measured by the scotch-bond test).
• the thickness of the Ni-P-ZF-particles film obtained by the method of the present invention is between about 0.3 microns to about 50 microns, more preferably between about 1 to aboutlO microns.
• the plating solution (pH 6.85) consisted of 0.3 M sodium citrate (Na 3 C 6 H 5 O 7 ), 0.1M sodium hypophosphate and 0.1 M ammonium chloride (NH 4 Cl).
• the concentration of cobalt (II) chloride (CoCl 2 ) was increased up to 0.1 M.
• the hydrazine (N 2 H 4 ) concentration was increased up to 0.3 M.
• the pH was controlled by increasing the sodium hydroxide (NaOH) concentration up to 1.25 M.
• /F-WS 2 particles were dispersed in the Co electroless bath by using an anionic surfactant, for example SDS (sodium dodecyl sulfate).
• SDS sodium dodecyl sulfate
• a film of Co with ZF-WS 2 particles was obtained by electrochemical plating.
• a stainless-steel plate (5x5 mm 2 ) was cleaned first by immersion in HF (20%) solution for 2 min. The plate was subsequently rinsed carefully in water and dried under N 2 gas stream. In the next step, the plate was immersed in a solution containing 40 ml CoCl 2 IM (and optionally 40 ml NiCl 2 IM) and 0.2 ml acetic acid was added to the solution to bring the pH to 3.5.
• a current of 1 mA was applied on the plate which served as cathode with Pt gauge as an anode.
• the stainless steel plate was rinsed and immersed in a similar solution but now containing 3 wt% of ZF-WS 2 , which was prepared by sonication. A current of ImA was applied for 20 second. A black film was obtained. The overall thickness of the film was about 6 micron.
• a mother solution of Zirconia is prepared. Glacial acetic acid (3 ml) is slowly added to 10 ml of zirconia tetrapropoxide (Zr(OCsH 7 ) 45 TPOZ) and stirred for 30 minutes. Then 20 ml of n-propanol (C 3 H 7 OH) is added to the solution, which is further stirred for 15 minutes at room temperature. The solution is hydrolyzed with 4 ml of 50% diluted solution of acetic acid in deionized (DI) water. Following this step, the solution is stirred for another 30 minutes at room temperature, filtered, and stored in a refrigerator for up to 4 days. The solution is transparent and its color pale yellow.
• DI deionized
• alcoholic suspension of the ZF-WS 2 nanoparticles is prepared by sonication of 10 mg of the nanoparticles and is added dropwise to the stirred mother solution. After that the articles are immersed in the suspension and after withdrawing (dip coating) and drying are annealed in 40 °C for an hour. The final step is annealing of the articles at 300 0 C in inert gas atmosphere.
• Friction and wear testing The tests were performed using a ball-on-flat device with a sliding velocity of
• Ni-P-IF-WS 2 coating with a wear track after 100 cycles of dry friction is shown in Fig. 4.
• Mouth Kote oral moisturizer
• the ball used was made of silicone nitride. Corrosion tracks on the surface of the ball were not observed, as can be seen in Fig. 5 A. The IF particles are observed on the surface of the silicon nitride ball before cleaning with hexane. No wear track and particles on the surface of the ball were observed after the cleaning, as can be seen in the photograph in Fig. 5B.
• the inventors compared the friction coefficient of an uncoated orthodontic wire substrate to that of a wire coated with a composite Of Ni-P-WS 2 .
• the graph in Fig. 6 shows the results of 30 cycles of this test, from which it is evident that after the first cycle the friction coefficient of the uiicoated wire was 0.1 and that of the coated wire was 0.08, while after 30 cycles the uncoated-wire friction coefficient was 0.25 and that of the coated wire was 0.05.
• the coated wires were compared to uncoated wires at conditions simulating the movement of the tooth and bracket on the wire in the mouth, by using the Instron assembly.
• the tests were set at 3 different angles of contact between the bracket and the wire. From the results presented in Fig. 6 it was obvious that a run-in period was needed before testing the wires on the Instron.
• the run-in period of the wire was done by repeated back and forth movements of the wire in a bracket slot before connecting the wire to the Instron.
• a different bracket was used for the Instron testing.
• Data is presented in Table I below and comparative graphs in Figs. 7-9 showing the relation between force and displacement of brackets where the peak indicates the maximum force needed to begin movement of the bracket on the wire (static friction).
• Table I Summary of Instron testing. Results or Force are in N ⁇ SD. The highest angle of 10° was tested in. the dry and wet mode. DI water was used instead of the Mouth Kote lubrication fluid due to the possible damage to the Instron equipment. Angles 5° and 10° were repeated in a reverse order for the purpose of investigating the effect of residual nanoparticles remaining in the bracket slot. The Instron results show a substantial reduction in the friction resistance to sliding at the different angles that were tested. At an angle of 0° the reduction of friction was 17%. As the angle grew to 5°, the reduction rate grew to 46% and the 10° angle showed a 54% reduction of friction compared to the uncoated wire.
• the coating of the wire with the composite Ni-P-ZF-WS 2 reduced the friction coefficient to 0.05 after a run-in period.
• the friction coefficient was elevated to 0.25. This could mean that the force needed for orthodontic movement grows with time on the uncoated wire and is reduced with time on the coated one.
• Instron tests were carried out in order to simulate the actual type of forces that develop during the orthodontic tooth movement. The Instron simulates the tilt in the wire with respect to the bracket and consequently the entire load is exerted on a small area of the bracket (on the corners), resulting in much higher friction. These tests resulted in the reduction of friction on the coated wire, a reduction that is pronounced with the elevation of the angle between the wire and the slot.
• Tribological tests in the wet mode using a saliva substitute resulted in increased friction coefficients for both coated and uncoated SS plates tested with a tempered steel ball.
• a reduction in the force (friction) was recorded. This difference is attributed to the corrosion that developed on the tempered steel ball tester and to the fact that a different type of fluid was in use.
• the reduction observed with the wire and bracket in the Instron was attributed to the lubrication potential of the DI water and the short duration of the test.
• the method developed here for coating the orthodontic archwire substrate was aimed at overcoming the poor adhesive strength of the coating to the wire, compared to the SS plates.
• Use of Ni or Ni-Cr + Ni by e-beam evaporation as an initiator of the electroless process was not sufficient.
• a conditioning step of etching the substrate by HF was needed for increasing the retention of the coating to the wire. The reason for the difference between the SS plate and the orthodontic wire is probably due to the finishing process and the flexibility of the wire, which can affect the bonding force between the coating and the wire.
• the coatings of the invention may be applied to other orthodontic materials as well.
• a self-ligating bracket for example, should show even lower friction levels when the coating is in use.
• this coating may be utilized in other biological systems where friction is a problem as in temporomandibular disorders or in hip replacements.
• the first step is degreasing by acetone followed by propanol, water rinse and drying under nitrogen flow.
• the wire is then treated in a plasma asher (March) for 5 min and a pure nickel film (lOOnm) is deposited by e-beam evaporation (Edwards Auto 306).
• Ni-P solution A commercial (ENPLATE Ni-425, Enthone Inc.) electroless plating Ni-P solution was used for the present experiments for coating the orthodontic wires (sds Ormco,California. 0.019x0.025 inch rectangular stainless steel arch wires) and the coating seemed to have poor adhesion as tested by a simple scotch bond test.
• a thin film of 80-20% nickel-chromium (Ni-Cr) was deposited by e-beam evaporation instead of a pure Ni film.
• Ni-Cr nickel-chromium
• the electroless reaction could not be initiated on this film.
• a layer of pure Ni was e-beam evaporated on the Ni-Cr film and plating was achieved.
• the triple layer coating seemed to have adequate adhesion strength tested by scotch-bond and by bending the wire.
• the next step was to add the inorganic fullerene-like nanoparticles of WS 2 (/F- WS 2 ) to the electroless plating solution in order to incorporate it into the Ni-P layer.
• WS 2 inorganic fullerene-like nanoparticles of WS 2
• 200mg of WS 2 were added to 100ml solution and dispersed by a magnetic stirrer.
• ZF-nanoparticles quickly agglomerated and precipitated.
• a series of surfactants were tested including Triton-x, sodium dodecylsulfate (SDS) and cetyltrimethylammoniumbromide (CTAB).
• CTAB cationic surfactant gave the best results but the amount of the agglomerated nanoparticles was still very high.
• an ultrasonic probe (sonifaier 150, Branson-30 watts output) was inserted into the solution for one minute. This resulted in an evenly dispersed solution that was stable for long periods of time. Transmission electron microscopy (model CM120, FEI)(TEM) analysis indicated that under these conditions the agglomerates of the IF nanoparticles could be suspended without damaging the nanoparticles.
• SS wires were coated.
• the wires were treated with 20% HF and were inserted in the electroless bath.
• a coating of Ni-P- TF-WS 2 was accomplished.
• Having a layer of Ni-Cr and/or Ni underneath the Ni-P-ZF- WS 2 further improved the continuous properties of the coating.
• the wires were then annealed at 400°C in N 2 atmosphere for one hour and then tested with a ball on flat tester as described above and compared to the uncoated wires.
• the Instron was set to move the bracket down along the wire at a constant speed of 10 rnrn/min to a distance of 5 mm.
• the test begins with, a steady increase in the force and reaches a maximum when movement begins on the wire. This maximum represents the static friction and is the force that is of interest in this case.
• Uncoated and coated wires were tested at the 3 different angles.
• the first tests on the coated wires resulted in high friction levels that were overcome by a run-in period of repeated back and forth movements of the wire in the bracket.
• the tests were further conducted in a wet mode with DI water dripping on the bracket and wire during the test simulating the saliva in the interface when the movement occurs in the mouth.
• the tests were repeated 5 times for each group and all the data was recorded onto the operating system of the INSTRON and then analyzed and plotted.
• Toxicology tests of the IF-WS 2 reported the material as being non-toxic in an oral administration in rats.
• the presence of Ni in orthodontic appliances is known and they are approved for use (except in people with an allergic sensitivity to Ni).
• the sequential method applied in this study represents a stepwise procedure, using a minimum amount of animals.
• volume dosage was 5 ml/kg.
• the oral route was chosen as the route of administration since in order to assess the toxic characteristics of substances the determination of acute oral toxicity is usually an initial step.
• the initial dose level selected was based on the Sponsor's specific request and according to the respective guideline.
• secretions and excretions e.g. diarrhea
• autonomic activity e.g. lacrimation, salivation, piloerection, pupil size, unusual respiratory pattern
• Evaluation included monitoring the relationship, if any, between the animals' exposure to the Test Item and the incidence and severity of all abnormalities including: effects on mortality, behavioral and clinical abnormalities, body weight changes, gross lesions, and any other toxic effects.
• Body weight gain of all animals was found to be within range of normally expected values.
• Test Item Inorganic fullerene-like WS 2 nanospheres (IF- WS 2 ) is allocated to "Category 5" or "Unclassified” in accordance with the classification by GHS (Globally Harmonized System) (e) .
• GHS Globally Harmonized System
• Table 1 Mortality Incidence Observed throughout the Entire 14-day Observation Period, in Female Sprague-DawleyTM Rats, Following a Single Oral Administration of Inorganic fullerene-like WS 2 nanospheres (IF-WS 2) (Batch No.: HP6):
• Inorganic fullerene-like WS 2 nanospheres IF n 6 (IF-WS 2 ) 0/6 (300 mg/kg)
• Table 2 Individual Clinical Signs Observed throughout the Entire 14-day Observation Period, in Female Sprague-DawleyTM Rats, Following a Single Oral Administration of Inorganic fullerene-like WS 2 nanospheres (IF-WS 2 ):
• NAD No Abnormality Detected T able 3: Individual and Mean ( ⁇ SD) Group Values of body Weights in Female Sprague-DawleyTM Rats, Following a Single Oral Administration of Inorganic fullerene-like WS 2 nanospheres (IF-WS 2):
• T able 5 Individual and Mean ( ⁇ SD) Group Values of Percentage (%) Body Weight Gain in Female Sprague-DawleyTM Rats, Following a Single Oral Administration of Inorganic fullerene-like WS 2 nanospheres (IF-WST) (Batch No.: HP6):
• Test Item Inorganic fullerene-like WS 2 nanospheres (IF- WS ⁇ ) (Batch No. HP6) was assessed on the basis of the testing procedure recommended by OECD Guideline for the Testing of Chemicals, Section 4, No. 423, "Acute Oral Toxicity - Acute Toxic Class Method", adopted December 17 th , 20001.
• Inorganic fullerene-like WS 2 nanospheres (IF-WS 2 ) (Batch No. HP6) was administered successively to two groups of n—6 female Sprague-Dawley (SDTM) rats per each dose levels of 300 and 2000 mg/kg.
• Test Item Inorganic fullerene-like WS 2 nanospheres (IF-WS 2 ) (Batch No. HP6) is allocated to "Category 5" or "Unclassified” in accordance with the classification by GHS (Globally Harmonized System) ⁇ .

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